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CVE-2020-15656· NVD / CVE Program· CNA mozilla

JIT optimizations involving the Javascript arguments object could confuse later optimizations.

Noroxi assessment

Priority: Monitor (action score 35/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 1.5% (FIRST EPSS); higher than 74% of all records.
  • Anyone who can reach it over the internet can trigger it. No account or password is required. A user must open a link or visit a page. No special conditions are required; it is repeatable.
  • Fixed version: MozillaFirefox (openSUSE:Leap 15.1) 78.1.0-lp151.2.61.1; MozillaFirefox (openSUSE:Leap 15.2) 78.1.0-lp152.2.15.1, 78.1.0-lp152.2.12.1; pipewire (openSUSE:Leap 15.2) 0.3.6-lp152.2.3.1.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to MozillaFirefox (openSUSE:Leap 15.1) 78.1.0-lp151.2.61.1; MozillaFirefox (openSUSE:Leap 15.2) 78.1.0-lp152.2.15.1, 78.1.0-lp152.2.12.1; pipewire (openSUSE:Leap 15.2) 0.3.6-lp152.2.3.1 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

JIT optimizations involving the Javascript arguments object could confuse later optimizations. This risk was already mitigated by various precautions in the code, resulting in this bug rated at only moderate severity. This vulnerability affects Firefox ESR < 78.1, Firefox < 79, and Thunderbird < 78.1.

HighCVSS 8.8 · v3.1—No exploit Fix available
Published
Aug 10, 2020
Updated
Jun 16, 2026
EPSS
1.5% · 74th percentile

Report tools

JSON

Action score

35

Monitor

Low priority for now.

CVSS
35 / 40 · 8.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 1.5%

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

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When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
mozillafirefox
mozillafirefox esr
mozillathunderbird
opensuseleap
canonicalubuntu linux

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • canonical ubuntu linux16.04
  • canonical ubuntu linux18.04
  • canonical ubuntu linux20.04
  • mozilla firefoxbefore 79.0
  • mozilla firefox esrbefore 78.1
  • mozilla thunderbirdbefore 78.1
  • opensuse leap15.2

Versions reported by the vendor

Affected version ranges reported by the assigning authority (mozilla). Independent of NVD's CPE analysis and usually ahead of it.

  • Mozilla Firefox

    • unspecified and later · before 79affected

  • Mozilla Firefox ESR

    • unspecified and later · before 78.1affected

  • Mozilla Thunderbird

    • unspecified and later · before 78.1affected

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
openSUSE:Leap 15.1MozillaFirefoxbefore 78.1.0-lp151.2.61.178.1.0-lp151.2.61.1
openSUSE:Leap 15.2MozillaFirefoxbefore 78.1.0-lp152.2.15.178.1.0-lp152.2.15.1
openSUSE:Leap 15.2MozillaFirefoxbefore 78.1.0-lp152.2.12.178.1.0-lp152.2.12.1
openSUSE:Leap 15.2pipewirebefore 0.3.6-lp152.2.3.10.3.6-lp152.2.3.1
Red Hat:enterprise_linux:7::clientfirefoxbefore 0:78.3.0-1.el7_90:78.3.0-1.el7_9
Red Hat:enterprise_linux:7::clientfirefox-debuginfobefore 0:78.3.0-1.el7_90:78.3.0-1.el7_9
Red Hat:enterprise_linux:8::appstreamfirefoxbefore 0:78.2.0-2.el8_20:78.2.0-2.el8_2
Red Hat:enterprise_linux:8::appstreamfirefox-debuginfobefore 0:78.2.0-2.el8_20:78.2.0-2.el8_2
Red Hat:enterprise_linux:8::appstreamfirefox-debugsourcebefore 0:78.2.0-2.el8_20:78.2.0-2.el8_2
Red Hat:rhel_e4s:8.0::appstreamfirefoxbefore 0:78.2.0-3.el8_00:78.2.0-3.el8_0
Red Hat:rhel_e4s:8.0::appstreamfirefox-debuginfobefore 0:78.2.0-3.el8_00:78.2.0-3.el8_0
Red Hat:rhel_e4s:8.0::appstreamfirefox-debugsourcebefore 0:78.2.0-3.el8_00:78.2.0-3.el8_0
Red Hat:rhel_eus:8.1::appstreamfirefoxbefore 0:78.2.0-3.el8_10:78.2.0-3.el8_1
Red Hat:rhel_eus:8.1::appstreamfirefox-debuginfobefore 0:78.2.0-3.el8_10:78.2.0-3.el8_1
Red Hat:rhel_eus:8.1::appstreamfirefox-debugsourcebefore 0:78.2.0-3.el8_10:78.2.0-3.el8_1
SUSE:HPE Helion OpenStack 8MozillaFirefoxbefore 78.1.0-112.8.178.1.0-112.8.1
SUSE:Linux Enterprise Module for Desktop Applications 15 SP1MozillaFirefoxbefore 78.1.0-3.100.278.1.0-3.100.2
SUSE:Linux Enterprise Module for Desktop Applications 15 SP2MozillaFirefoxbefore 78.1.0-8.3.178.1.0-8.3.1
SUSE:Linux Enterprise Module for Desktop Applications 15 SP2MozillaFirefox-branding-SLEbefore 78-9.2.478-9.2.4
SUSE:Linux Enterprise Module for Desktop Applications 15 SP2pipewirebefore 0.3.6-3.3.20.3.6-3.3.2
SUSE:Linux Enterprise Server 11 SP4-LTSSMozillaFirefoxbefore 78.1.0-78.87.178.1.0-78.87.1

Same product

mozilla: all records

Other highest-scoring records for the same primary product.

  • CVE-2010-3765Mozilla Firefox 3.5.x through 3.5.14 and 3.6.x through 3.6.11, Thunderbird 3.1.6 before 3.1.6 and 3.0.x before 3.0.10, and SeaMonkey 2.x befKEV
    94Now
  • CVE-2019-11708Insufficient vetting of parameters passed with the Prompt:Open IPC message between child and parent processes can result in the non-sandboxeKEV
    87Now
  • CVE-2015-4495The PDF reader in Mozilla Firefox before 39.0.3, Firefox ESR 38.x before 38.1.1, and Firefox OS before 2.2 allows remote attackers to bypassKEV
    86Now

Published before and after this one in the same product

  • ← EarlierCVE-2020-15654Aug 10, 2020 · When in an endless loop, a website specifying a custom cursor using CSS could make it look like the user is interacting with the user interf
    26Monitor
  • ← EarlierCVE-2020-15655Aug 10, 2020 · A redirected HTTP request which is observed or modified through a web extension could bypass existing CORS checks, leading to potential disc
    26Monitor
  • Later →CVE-2020-15657Aug 10, 2020 · Firefox could be made to load attacker-supplied DLL files from the installation directory.
    31Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
opensuse:MozillaFirefox78.1.0-lp151.2.61.1 · openSUSE:Leap 15.1Package registry (OSV)
opensuse:pipewire0.3.6-lp152.2.3.1 · openSUSE:Leap 15.2Package registry (OSV)
red hat:firefox0:78.2.0-3.el8_0 · Red Hat:rhel_e4s:8.0::appstreamPackage registry (OSV)
red hat:firefox-debuginfo0:78.2.0-3.el8_0 · Red Hat:rhel_e4s:8.0::appstreamPackage registry (OSV)
red hat:firefox-debugsource0:78.2.0-3.el8_0 · Red Hat:rhel_e4s:8.0::appstreamPackage registry (OSV)
suse:MozillaFirefox78.1.0-78.87.1 · SUSE:Linux Enterprise Server 11 SP4-LTSSPackage registry (OSV)
suse:MozillaFirefox-branding-SLE78-9.2.4 · SUSE:Linux Enterprise Module for Desktop Applications 15 SP2Package registry (OSV)
suse:pipewire0.3.6-3.3.2 · SUSE:Linux Enterprise Module for Desktop Applications 15 SP2Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

All national notices →

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • A user must open a link or visit a page.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
high · data or configuration can be modified
Availability
high · the service can be disrupted
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
Required
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

CWE-843 · Access of Resource Using Incompatible Type ('Type Confusion')

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (5 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records